Answer:
a) 19/12 or 1 7/12
b) 5/21
Step-by-step explanation:
A useful formula for sums of fractions is ...
a/b + c/d = (ad +bc)/(bd)
_____
a)
3/4 +5/6 = (3·6 +4·5)/(4·6) = (18 +20)/24 = 38/24 = 19/12 = 1 7/12
__
b)
4/7 -1/3 = (4·3 -7·1)/(7·3) = (12 -7)/21 = 5/21
